Maternal Vitamin D Status in Type 1 Diabetic Pregnancy: Impact on Neonatal Vitamin D Status and Association with Maternal Glycaemic Control

Sarah E Bennett,Ann Mcginty,David R Mccance,John G Manderson,Philip Johnston,Rachel Mcgalliard,Jennifer Mcpeake,Franco Folli

doi:10.1371/journal.pone.0074068

Sarah E Bennett, Ann Mcginty + Show 6 more

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https://doi.org/10.1371/journal.pone.0074068

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Abstract

ObjectiveThe first aim of this study was to assess 25-hydroxy vitamin D (25OHD) concentrations in women with type 1 diabetes (T1DM) during pregnancy, post-delivery and also foetal (cord blood) 25OHD concentrations and to examine relationships between these. The second aim of the study was to investigate potential interactions between maternal body mass index (BMI) and foetal vitamin D status. A further study aim was to examine potential relationships between maternal 25OHD and glycosylated haemoglobin (HbA1c) throughout pregnancy.Research Design and MethodsThis was an observational study of 52 pregnant controls without diabetes and 65 pregnant women with T1DM in a university teaching hospital. Maternal serum 25OHD was measured serially throughout the pregnancy and post-delivery. Cord blood 25OHD was measured at delivery. 25OHD was measured by liquid chromatography tandem mass spectrometry (LC-MS/MS).ResultsVitamin D deficiency (25OHD <25 nmol/L) was apparent in both the T1DM subjects and controls at all 3 pregnancy trimesters. Vitamin D levels in all cord blood were <50 nmol/L. Maternal 25OHD correlated positively with cord 25OHD at all 3 trimesters in the T1DM group (p = 0.02; p<0.001; p<0.001). 25OHD levels within cord blood were significantly lower for women with diabetes classified as obese vs. normal weight at booking [normal weight BMI <25 kg/m2 vs. obese BMI >30 kg/m2 (nmol/L±SD); 19.93±11.15 vs. 13.73±4.74, p = 0.026]. In the T1DM group, HbA1c at booking was significantly negatively correlated with maternal 25OHD at all 3 trimesters (p = 0.004; p = 0.001; p = 0.05).ConclusionIn T1DM pregnancy, low vitamin D levels persist throughout gestation and post-delivery. Cord blood vitamin D levels correlate with those of the mother, and are significantly lower in obese women than in their normal weight counterparts. Maternal vitamin D levels exhibit a significant negative relationship with HbA1c levels, supporting a potential role for this vitamin in maintaining glycaemic control.

Highlights

It is well established that vitamin D plays a primary role in bone health, with severe vitamin D deficiency known to cause rickets in children and osteomalacia in adults [1]
Maternal 25OHD correlated positively with cord 25OHD at all 3 trimesters in the T1DM group (p = 0.02; p,0.001; p,0.001). 25OHD levels within cord blood were significantly lower for women with diabetes classified as obese vs. normal weight at booking [normal weight body mass index (BMI),25 kg/m2 vs. obese BMI .30 kg/m2; 19.93611.15 vs. 13.7364.74, p = 0.026]
In T1DM pregnancy, low vitamin D levels persist throughout gestation and post-delivery

Summary

Introduction

It is well established that vitamin D plays a primary role in bone health, with severe vitamin D deficiency known to cause rickets in children and osteomalacia in adults [1]. Vitamin D has been linked to a wide variety of other non-bone health outcomes such as; cardiovascular disease, cancer, autoimmune diseases and type 1 and type 2 diabetes mellitus (T1DM, T2DM; [2]). Vitamin D status is assessed by measuring circulating concentrations of 25-hydroxy vitamin D (25OHD). In relation to bone health, a 25OHD level of ,25 nmol/l is currently defined as deficient [3]; the cut-off level for sufficiency remains unclear. Holick [4] suggests that for extraskeletal health, sufficiency is achieved at vitamin D levels .75 nmol/l. Hypovitaminosis D is commonly seen in both pregnant and non-pregnant women worldwide [5]; with many factors impacting on vitamin D status, including; exposure to sunlight, skin colour, season, latitude and obesity, among others [6]

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